| 摘要 |
PURPOSE:To increase both the responsiveness and the stability of a control system, by holding the drawing-down force at a certain level at the side opposite to the working side where the hydraulic pressure is affected to the cylinder ram of a drawing-down cylinder by applying separately to the drawing- down cylinder. CONSTITUTION:The displacement of a cylinder ram 4 is detected by a displacement detector 6 and supplied to a servo amplifier 7, and the control signal is delivered to a servo valve 9 by the set value 8 to be applied to control the hydraulic pressure which is supplied to a drawing-down cylinder 3. A pressure controlling system 10 is set at the side B opposite to the pressure working side A to maintain a certain level of drawing-down force. In other words, the pressure of the pressure oil supplied from a servo valve 11 is detected by a pressure detector 12, and this output signal is supplied to a servo amplifier 13 to be compared with the set value 14. Then the control signal is supplied to the valve 11 of the system 10 to control the valve 11. Thus the pressure is increased although the pressure of the cylinder 3 is low, and the differential pressure of the valve 11 has no change between the rising and falling modes of the ram 4. |
